This invention relates in general to a gas discharge surge arrester.
Surge arresters are known in the prior art which are housed in a vacuum-tight housing structure and having at least one cylindrical insulating ring with first and second electrodes and an ignition gap located between the two electrodes, wherein at least a first electrode is partially covered with an activating layer and wherein the electron work function of the activating layer is lower than that of the electrode material. Such a surge arrester is disclosed in U.S. Pat. No. 3,649,874. A three-electrode surge arrester of similar construction is disclosed in U.S. Pat. No. 3,710,191. Both patents disclose surge arresters in which an activating layer is arranged in discharge gaps where it reduces the electron work function.
The present invention overcomes the drawbacks of the prior art and provides improvements which consist in reducing the divergence of the electrical values, in particular the response voltage, of surge arresters during their life duration. Furthermore, operational reliability of these surge arresters is improved with the present invention.